Size of the universe

The size of the universe refers to the relative size of the universe and entities contained within it. The universe is vast; it has been expanding for almost 13.8 billion years at a considerable fraction of the speed of light,[1] so it is roughly 13 billion light years across. This means that the universe is ~1.3 x 1026 m across. For a reference of size, humans are usually under 2 m tall, atoms are approximately 10-10 m across, and nuclei are approximately 10-15 m across.[2] There is a difference of a factor of 1041 between the universe and a nucleus, which can be written out as 100 000 000 000 000 000 000 000 000 000 000 000 000 000, a number so large it is hard to wrap one's head around.

Here are some useful on-line tools that compare the sizes of various objects in the universe:

  • The King Centre for visualization in science[3], specifically their scale of the cosmos
  • The htwins project (click on the start button and then click on the notes to mute the music)
  • Hyperphysics has a nice analogy here that helps scale the size of the universe.

Here is a video from IMAX cosmic voyage which demonstrates size comparisons between various entities (music from "The Matrix" movie-trilogy and "Awake" by Jake Kaufman):

Please contact us with other tools showing the size of the universe in interesting ways.

For Further Reading


  1. For some interesting reading please see:
  2. Sears and Zemanski's University Physics, 13th edition by Young and Freedman. Addison Wesley, 2010. Chapter 43, pg 1440.

Authors and Editors

Sarjana Amin, Allison Campbell, Ashley Sheardown, Kailyn Stenhouse, Jason Donev
Last updated: October 15, 2021
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